Medical suction tube and suction control apparatus for endoscope

ABSTRACT

A medical suction tube which is opened at the distal end thereof and connected at the proximal end thereof to a suction means. A linear cut is made in the intermediate portion of the tube so as to extend obliquely from the proximal end side toward the distal end side of the tube so that, when the tube is bent, the cut is opened and ambient air is sucked into the tube through the cut, whereas, when the tube is straightened, the cut is closed and suction is performed through the distal end opening. A suction control apparatus for an endoscope that utilizes the above-described medical suction tube. The suction control apparatus has a switching element for switching over the following two states from one to the, that is, a state wherein the tube is bent with the cut facing outward and a state wherein the tube is straightened at and near the cut, so that, when the tube is bent, the cut is opened and the ambient air is sucked into the tube through the cut, whereas, when the tube is straightened, the cut is closed and suction is performed through a suction port at the distal end of the endoscope.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a medical suction tube employed to suckmucus and mucous membrane from a hollow organ of the patient's body andalso pertains to a suction control apparatus for an endoscope thatutilizes such a suction tube.

2. Description of the Related Art

A typical conventional medical suction tube has an on-off valveconnected to the intermediate portion of the tube so that the tube isopened and closed by the valve. However, in the case where the tube ismade disposable for sanitary reasons, for example, the valve which comesinto contact with the sucked mucus and mucous membrane must also bedisposed of after use for a single procedure and, therefore, the costbecomes considerably high.

To overcome the above-described disadvantage, there has heretofore beena prior art wherein a flexible tube is closed by pressing it sidewardand, when the tube is released from the pressure, the tube returns toits previous open state by its own restoring force. With this prior artdevice, the sucked mucus and mucous membrane do not come into contactwith any other elements than the tube and, therefore, it is onlynecessary to dispose of the tube alone after use for a single procedure.

However, this prior art medical suction tube necessitates an operationof closing the tube itself by pressing it sideward and this operationrequires the application of a great deal of force continuously for acertain period of time.

It may be considered is possible to reduce the wall thickness of thetube in order to minimize the amount of force required to press thetube. However, a reduction in the wall thickness of the tube lowers therestoring force of the tube which is expected to act when the tube isreleased from the pressure, or may cause the tube to be closed when thesuction force is applied thereto and results in a failure to effect asuction operation.

A suction control apparatus for an endoscope is usually provided on thecontrol part of the endoscope and, in many cases, the suction controlapparatus has a structure wherein a piston is reciprocatably fitted in acylinder connected to a suction tube which opens at the distal end ofthe insert part of the endoscope.

In such a suction control apparatus, however, the number of parts islarge and the structure is complicated and, therefore, the parts arelikely to be clogged with the mucus and mucous membrane sucked throughthe tube. The mucus and mucous membrane are considerably difficult towash off completely and therefore give rise to unsanitary conditions.

Under these circumstances, there has heretofore been a suction controlapparatus wherein the suction tube is normally closed by pressing itsideward within the control part and, when a suction operation is to beconducted, the suction tube is opened by removing the pressuretherefrom. With this arrangement, the sucked mucus and mucous membranedo not come into contact with any other elements than the tube and,therefore, washing conducted after use is facilitated. However, a greatdeal of force is needed to press the tube itself sidewardly so as toclose it, and the operability of the prior art is therefore considerablylow.

The amount of force required to press the tube may be minimized byreducing the wall thickness of the tube. However, a reduction in thewall thickness of the tube lowers the restoring force of the tube whichis expected to act when the tube is released from the pressure, or maycause the tube to be closed when the suction force is applied theretoand result in a failure to effect a suction operation, as in the case ofthe above-described medical suction tube.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a medical suction tubewhich is designed so that a suction operation can be effectively andreliably controlled with an extremely simple structure and with a smallamount of force, and also provide a suction control apparatus for anendoscope which facilitates washing and is highly sanitary and whichfurther has a simple structure and enables a suction operation to becontrolled with a small amount of force.

Other objects and advantages of the present invention will becomeapparent from the following detailed description of illustratedembodiments of the invention.

According to the present invention, there is provided a medical suctiontube connected at the proximal end thereof to a suction means,comprising: an opening formed at the distal end of the tube; and a cutmade in the intermediate portion of the tube so as to extend obliquelyfrom the proximal end side toward the distal end side of the tube,whereby, when the tube is bent, the cut is opened and ambient air issucked into the tube through the cut, and, when the tube isstraightened, the cut is closed and suction is performed through theopening.

In addition, there is provided a suction control apparatus provided on acontrol part of an endoscope having a suction port at the distal end ofan insert part thereof, comprising: a flexible tube communicating at thedistal end thereof with the suction port and communicably connected atthe proximal end thereof to a suction means; a cut made in theintermediate portion of the tube so as to extend obliquely from theproximal end side toward the distal end side of the tube; and aswitching device for switching over the following two states from one tothe other; that is, a state wherein the tube is bent with the cut facingoutward and a state wherein the tube is straightened at and near thecut, whereby, when the tube is bent, the cut is opened and ambient airis sucked into the tube through the cut, whereas, when the tube isstraightened, the cut is closed and suction is performed through thesuction port.

In addition, there is provided a suction control apparatus provided on acontrol part of an endoscope having a suction port at the distal end ofan insert part thereof, comprising: a flexible tube communicating at thedistal end thereof with the suction port and communicably connected atthe proximal end thereof to a suction means; a cut made in theintermediate portion of the tube so as to extend obliquely from theproximal end side toward the distal end side of the tube; and aswitching device for switching over the following two states from one tothe other; that is, a stand-by state wherein the tube is diametricallypressed at the cut from the side of the tube where the cut is providedso as to close the cut area which leads to the distal end of the tubeand a suction state wherein the tube is restored to its free state,thereby enabling suction to take place from the distal end side to theproximal end side of the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more fully understood from the descriptionof preferred embodiments of the invention set forth below, together withthe accompanying drawings, in which:

FIG. 1 is a sectional side view of a first embodiment of the medicalsuction tube according to the present invention;

FIG. 2 is a sectional side view of the tube shown in FIG. 1, which showsthe tube in a bent state;

FIG. 3 is a sectional side view of a second embodiment of the medicalsuction tube according to the present invention;

FIG. 4 is a sectional side view of the tube shown in FIG. 3, which showsthe tube in a straightened state;

FIGS. 5 to 7 are sectional side views, respectively, showing first tothird experiments;

FIG. 8 is a schematic view showing the general arrangement of anendoscope incorporating one embodiment of the suction control apparatusaccording to the present invention;

FIG. 9 is a fragmentary sectional side view of the suction controlapparatus in a state wherein the control button is pushed in;

FIG. 10 is a sectional front view of a slider having a C-shapedcross-sectional configuration;

FIG. 11 is a schematic view showing the general arrangement of anendoscope incorporating another embodiment of the suction controlapparatus according to the present invention;

FIG. 12 is a fragmentary side view of a tube employed in the suctioncontrol apparatus shown in FIG. 11;

FIG. 13 is a sectional plan view of the pressing plate and the tubeemployed in the suction control apparatus shown in FIG. 11; and

FIG. 14 is a fragmentary enlarged sectional side view of the suctioncontrol apparatus shown in FIG. 11 in a state wherein the control buttonis pushed in.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described below in detailwith reference to the accompanying drawings.

FIGS. 1 and 2 show in combination a first embodiment of the medicalsuction tube according to the present invention. In the figures, thereference numeral 1 denotes a flexible tube which is made, for example,of elastomer, tetrafluoroethylene resin, etc. Therefore, the tube 1 hassuperior chemical resistance. The tube 1 has an open distal end which isdefined as a distal end opening 2. The proximal end of the tube 1 isconnected to a suction means 3. It should be noted that the opening 2may be provided on the side of the tube 1.

A linear cut 4 is made in the intermediate portion of the tube 1 so asto extend obliquely from the proximal end side toward the distal endside of the tube 1. For example, the cut 4 is made with a sharp-edgedtool such as a razor so that the cut 4 is at 30 degrees to the axis ofthe tube 1 and extends to a depth which is equal to about two thirds ofthe diameter of the tube 1.

The arrangement is such that, when the tube 1 is straightened at andnear the cut 4, the cut 4 is closed as shown in FIG. 1, whereas, whenthe tube 1 is bent with the cut 4 facing outward, the cut 4 is opened tothe open air as shown in FIG. 2.

In the first embodiment arranged as described above, the tube 1 isformed such that it is normally straight at and near the cut 4 and hencethe cut 4 is closed in a normal state, as shown in FIG. 1. Accordingly,if the suction means 3 is activated in this state, suction is performedthrough the distal end opening 2. This embodiment is therefore suitablefor uses in which suction is steadily conducted.

When the tube 1 is pushed from one side thereof so that the tube 1 isbent with the cut 4 facing outward, the cut 4 is opened to the open air,as shown in FIG. 2. Accordingly, the air is sucked into the tube 1through the cut 4 and the suction through the distal end opening 2 issuspended.

FIGS. 3 and 4 show in combination a second embodiment of the presentinvention, in which a tube 11 is bent so that the cut 4 normally opensto ambient air. Accordingly, opposite to the first embodiment, thisembodiment is arranged such that, when the tube 11 is in a normal state,the air is sucked through the cut 4 and no suction is performed throughthe distal end opening 2, as shown in FIG. 3. When the tube 11 isstraightened, the cut 4 is closed and suction is performed through thedistal end opening 2, as shown in FIG. 4.

The effects of the direction and depth of the cut 4 in each embodimenthave been confirmed by the following experiments.

FIGS. 5 to 7 show first to third experiments, respectively, which wereconducted under the same conditions except for the cuts 24a, 24b and 24cmade in the respective tubes 21. In these experiments, flexible tubes 21having an inner diameter of 2.6 mm and an outer diameter of 4 mm wereused and water contained in a water tank was sucked through the distalend opening 22 by a suction means 23 (the vacuum used being about 250mmHg) connected to the proximal end of each of the tubes 21. Each tube21 was bent in the form of an arc having a radius of about 25 mm. In theexperiments, the cuts 24a, 24b and 24c were disposed at the respectivetops of the bent tubes 21 so as to normally open to ambient air.

In the first experiment, the cut 24a was, as shown in FIG. 5, linearlymade in the tube 21 so as to extend obliquely from the proximal end side(i.e., the suction means side) toward the distal end side (i.e., thedistal end opening side) of the tube 21 in the same way as in theabove-described embodiments. In this experiment, a large amount of airwas sucked into the tube 21 through the cut 24a and, therefore,substantially no water was sucked up into the distal end opening 22, asshown in FIG. 5.

In the second experiment, the cut 24b was, as shown in FIG. 6, made inthe tube 21 so as to extend obliquely from the distal end side towardthe proximal end side of the tube 21 in reverse relation to the firstexperiment. In this case also, the air was sucked into the tube 21through the cut 24b. However, in contrast to the first experiment, avacuum was produced in the tube 21 between the cut 24b and the distalend opening 22 and water was sucked up into the tube 21 as far as thevicinity of the cut 24b.

In the third experiment, the cut 24c was formed by boring a hole in thetube 21 from one side thereof, the hole having a diameter of about 4 mmin the axial direction of the tube 21. In this case, a high vacuum wasproduced in the tube 21 between the cut 24c and the distal end opening22 and water was sucked up as far as the cut 24c. As a result, a smallamount of water leaked out through the cut 24c and also a small amountof water was sucked into the suction means 23.

It will be clear from the above-described experimental results that, ifa cut is linearly made in the tube 21 so as to extend obliquely from theproximal end side toward the distal end side of the tube 21 as in thecase of the cut 24a, when the tube 21 was bent with the cut facingoutward, substantially no vacuum acts at the distal end opening 22 ofthe tube 21.

Although in the above-described embodiments the angle of the cut 4 tothe axis of the tube 1 is set at 30 degrees and the depth of the cut 4is set at about two thirds of the diameter of the tube 1, it should benoted that the present invention is not necessarily limited thereto.More specifically, the angle and depth of the cut may be set as desired,provided that a cut is linearly made in the tube such as to extendobliquely from the proximal end side toward the distal end side of thetube so that, when the tube is straightened at and near the cut, the cutis closed, whereas, when the tube is bent with the cut facing outward,the cut is opened to ambient air and substantially no suction isperformed through the distal end opening. In practical use, the angle ofthe cut to the axis of the tube is preferably set in the range of from15 to 60 degrees.

Thus, according to the medical suction tube of the present invention, aflexible tube itself is provided with a cut so that the suctionoperation is controlled by bending or straightening the tube.Accordingly, the structure of the suction tube is extremely simple andthe cost thereof is considerably low; therefore, it is possible to makeit disposable. In addition, it is possible to control a suctionoperation with ease. Since the operability is not impaired even if ahard plastic tube is employed, it is possible to select a tube having anecessary level of hardness so as to conduct an effective and reliablesuction operation.

FIG. 8 shows an embodiment in which the above-described medical suctiontube is applied to a suction control apparatus for an endoscope.

In FIG. 8, the reference numeral 31 denotes a control part of anendoscope. A flexible tube 32 made, for example, of elastomer,tetrafluoroethylene, etc., is disposed inside the control part 31. Theproximal end of the tube 32 is communicably connected with a suctionmeans 33, while the distal end of the tube 32 is communicably connectedwith a suction port 35 which is opened at the distal end of the insertpart 34 of the endoscope. Accordingly, it is possible to suck up mucusand mucous membrane from a hollow organ of the patient's body into thesuction means 33 from the suction port 35 through the tube 32. It shouldbe noted that the tube 32 may be disposed along the outside of thecontrol part 31 and the insert part 34 and may also be arranged so as tobe detachable from to the endoscope.

The tube 32 is disposed in such a manner that it is bent inside thecontrol part 31. A linear cut 36 is made in the outer side of the bentportion of the tube 32 so as to extend obliquely from the proximal endside toward the distal end side of the tube 32. For example, the cut 36is made with a sharp-edged toll such as a razor so that the cut 36 is at30 degrees to the axis of the tube 32 and extends to a depth which isequal to about two thirds of the diameter of the tube 32. In practicaluse, the angle of the cut 36 should be selected so as to fall within therange of from 15 to 60 degrees. The arrangement is such that, when thetube 32 is bent with the cut 36 facing outward, the cut 36 is opened tothe ambient air as shown in FIG. 8, whereas, when the tube 32 isstraightened at and near the cut 36, the cut 36 is closed as shown inFIG. 9.

The control part 31 is provided with a slider 37 which is slidable alongthe outer surface of the tube 32. The slider 37 is formed in a tubularshape so that, when the tube 32 is curved, that portion of the tube 32which is within the slider 37 extends substantially straight.Accordingly, when that portion of the tube 32 which is provided with thecut 36 is within the slider 37, a flap 36a which is formed at the distalend side of the cut 36 is pressed by the slider 37 so as to close thecut 36, thereby preventing ambient air from entering the tube 32 throughthe cut 36.

The slider 37 is coupled to a control button 38 through a connecting rod37a. The control button 38 is reciprocatably fitted in a cylinder 39which is secured to the control part 31. The control button 38 isconstantly biased outward (leftward as viewed in FIG. 8) by the actionof a compression coil spring 40 which is interposed between the controlbutton 38 and the cylinder 39. Accordingly, in a stand-by state, theslider 37 is at a position which is closer to the suction port 35 thanthe cut 36. When the control button 38 is pushed in, the slider 37slides along the outer surface of the tube 32 to a position where itcovers the cut 36. The reference numeral 38a denotes a stopper for thecontrol button 38.

The operation of the embodiment arranged as described above will beexplained below.

In a stand-by state, the cut 36 opens to the open air, as shown in FIG.8. Accordingly, when the suction means 33 is activated in this state,the air is sucked into the tube 32 through the cut 36 and no suction isperformed through the suction port 35.

When the control button 38 is pushed in as shown in FIG. 9, the slider37 presses the flap 36a so as to close the cut 36, thereby preventingthe air from entering the tube 32 through the cut 36, and thus enablingsuction to take place through the suction port 35 at the distal end ofthe insert part 34. At this time, the cut 36 is completely covered withthe slider 37 and thereby entirely shielded from air and it is thereforepossible to eliminate completely the fear that the sucked mucus andmucous membrane will leak out through the cut 36.

It should be noted that the slider 37 may be formed in a C-shapedcross-sectional configuration as shown by the reference numeral 47 inFIG. 10. By doing so, the tube 32 can be readily attached to and removedfrom the slider 47 through the opening in the C-shaped configuration.

Thus, according to the endoscope suction control apparatus of thepresent invention, the sucked mucus and mucous membrane come intocontact only with the inner surface of the tube and it is thereforepossible to conduct washing readily and completely after use of theendoscope. Accordingly, the suction control apparatus of the presentinvention is highly sanitary.

Since a suction operation can be controlled simply by bending orstraightening a tube provided with a cut, the structure of the suctioncontrol apparatus is simple and it is possible to operate the apparatuswith a relatively small amount of force. In addition, since the tube hasa simple structure and is less costly, it is enable to be disposed ofafter use for a single procedure.

FIG. 11 shows another embodiment of the suction control apparatus for anendoscope according to the present invention. In this figure, thereference numeral 51 denotes a control part of an endoscope. A flexibletube 52 made, for example, of elastomer, tetrafluoroethylene, etc., isdisposed inside the control part 51. The proximal end of the tube 52 iscommunicably connected with a suction means 53, while the distal end ofthe tube 52 is communicably connected with a suction port 55 which isopened at the distal end of the insert part 54 of the endoscope.Accordingly, it is possible to suck up mucus and mucous membrane from ahollow organ of the patient's body into the suction means 53 from thesuction port 55 through the tube 52.

It should be noted that the tube 52 may be disposed along the outside ofthe control part 51 and the insert part 54 and may also be arranged soas to be detachable from the endoscope. The intermediate portion of thetube 52 may be constructed of a plurality of tube members which areconnected in series.

That portion of the tube 52 which is within the control part 51 isprovided with a linear cut 56 which extends obliquely from the proximalend side (i.e., the suction means side) toward the distal end side ofthe tube 52, as also shown in FIG. 12. For example, the cut 56 is madewith a sharp-edged tool such as a razor so that the cut 56 is at 30degrees (any angle within the range of from 15 to 60 degrees beingpossible to select) to the axis of the tube 52 and extends to a depthwhich is equal to about two thirds of the diameter of the tube 52. Aflap 56a which is formed at the distal end of the cut 56 is set in sucha manner that the outer surface of the tip of the flap 56a is disposedat the inner side of that portion of the tube 52 which is at theproximal end side of the cut 56, as shown in FIG. 14.

Referring back to FIG. 11, the control part 51 is provided with apressing plate 57 which is slidable in the diametrical direction of thetube 52 so that the pressing plate 57 can press the flap 56a from theside of the tube 52 where the cut 56 is provided so as to close the tube52. As shown in FIG. 13, the pressing plate 57 is provided with a bore57a for receiving the tube 52. The wall of the bore 57a which is pressedagainst the tube 52 is formed so as to extend in a straight line. Oneside of the bore 57a is open as shown by the reference numeral 57b sothat the tube 57a can be inserted into and removed from the bore 52therethrough when the tube 52 is assembled or replaced.

That portion of the tube 52 which is at and near the cut 56 is insertedinto a guide groove 51a formed in the control part 51 so that saidportion of the tube 52 will not be moved in the direction in which theflap 56a is pressed by the pressing plate 57. Accordingly, when the flap56a is pressed by the pressing plate 57 from the side of the tube 52wherein the cut 56 is provided, the flap 56a is pressed against the wallof the tube 52 which abuts on the inner wall 51b of the control part 51,thus closing the cut area which leads to the distal end portion of thetube 52, as shown in FIGS. 11 and 13.

The pressing plate 57 is coupled to a control button 58 through aconnecting rod 58a. The control button 58 is reciprocatably fitted in aretaining member 59 and constantly biased outward (leftward as viewed inFIG. 11) by the action of a compression coil spring 60 which isinterposed between the control button 58 and the control part 51.Accordingly, in a stand-by state, the pressing plate 57 constantlypresses the tube 52. However, when the control button 58 is pushed in,the pressing plate 57 is moved away from the tube 52, thus releasing thetube 52 from the pressed state.

The operation of the embodiment arranged as described above will next beexplained. In a stand-by state, the tube 52 is pressed by the pressingplate 57, as shown in FIGS. 11 and 13. Thus, since the cut area thatleads to the suction port 55 at the distal end of the insert part 54 isclosed, even if the suction means 53 is activated, no suction isperformed through the suction port 55 but ambient air is sucked into thetube 52 through the open cut 56 instead. At this time, even if mucus andmucous membrane enter the tube 52 through the suction port 55 due to,for example, a rise in pressure inside a hollow organ of the patient'sbody, the mucus mucous membrane are blocked by the reverse side of theflap 56a that is closing the tube 52, as shown by the reference numeral70 in FIG. 11. If the tube 52 should be incompletely closed at saidportion, the mucus and mucous membrane 70 are sucked up in small amountstoward the suction means 53 which is activated at all times and there isno fear of the mucus and mucous membrane 70 leaking to the outside.

When the control button 58 is pushed in as shown in FIG. 14, the tube 52is released from the pressed state and the cut 56 in the tube 52 isclosed so that no air enters the tube 52 through the cut 56. Inconsequence, suction is performed through the suction port 55 at thedistal end of the insert part 54. At this time, the flap 56a that is atthe distal end side of the cut 56 is restored to its previous positionby virtue of the resilience and the outer surface of the tip of the flap56a is pressed against the inner side of that portion of the tube 52which is at the proximal end side of the cut 56, as shown in FIG. 14.Accordingly, there is no fear of the sucked mucus and mucous membraneleaking out at this portion of the tube 52.

If the tube 52 is covered at and near the cut 56 with a non-rigid bagmember, leakage prevention becomes even more effective, so that, if thesucked mucus and mucous membrane should leak out through the cut 56, itis possible to prevent them from leaking to the outside.

Thus, the endoscope suction control apparatus according to the presentinvention enables a suction state and a stand-by state to be switchedover from one to the other simply be sidewardly pressing that portion ofthe tube which is provided with a cut. Therefore, the apparatus isextremely simple in structure and requires only a small amount of forceto operate the apparatus and therefore is superior in operability. As aresult, it is possible to employ a thick-walled tube and hence possibleto completely prevent crushing of the tube during suction.

Further, in the suction control apparatus of the present invention, thesucked mucus and mucous membrane come into contact only with the innersurface of the tube and it is therefore possible to arrange theapparatus such that the tube alone is disposed of after use so as toprevent the transmission of bacteria and viruses from one patient toanother. Thus, the suction control apparatus of the present invention isalso highly sanitary of view.

While the invention has been described by reference to specificembodiments chosen for purposed of illustration, it should be apparentthat numerous modifications could be made thereto by those skilled inthe art without departing from the basic concept and scope of theinvention.

What is claimed is:
 1. A suction control apparatus provided on a controlpart of an endoscope having a suction port at the distal end of aninsert part thereof, comprising:a flexible tube communicating at thedistal end thereof with said suction port and communicably connected atthe proximal end thereof to a suction means; a cut made in theintermediate portion of said tube so as to extend obliquely; andswitching means to bend and straighten a portion of said tube forswitching over the following two states from one to the other, that is,a state wherein said tube is bent with said cut facing outward and astate wherein said tube is straightened at and near said cut, whereby,when said tube is bent, said cut is opened and ambient air is suckedinto said tube through said cut, whereas, when said tube isstraightened, said cut is closed and suction is performed through saidsuction port.
 2. A suction control apparatus provided on a control partof an endoscope having a suction port at the distal end of an insertpart thereof, comprising:a flexible tube communicating at the distal endthereof with said suction port and communicably connected at theproximal end thereof to a suction means; a cut made in the intermediateportion of said tube so as to extend obliquely from the proximal endside toward the distal end side of said tube; and switching means tobend and straighten a portion of said tube for switching over thefollowing two states from one to the other, that is, a state whereinsaid tube is bent with said cut facing outward and a state wherein saidtube is straightened at and near said cut, whereby, when said tube isbent, said cut is opened and ambient air is sucked into said tubethrough said cut, whereas, when said tube is straightened, said cut isclosed and suction is performed through said suction port.
 3. A suctioncontrol apparatus according to claim 2, wherein said tube is made ofelastomer.
 4. A suction control apparatus according to claim 2, whereinsaid cut is at an angle of from 15 to 60 degrees to the axis of saidtube.
 5. A suction control apparatus according to claim 4, wherein saidcut is at an angle of 30 degrees to the axis of said tube.
 6. A suctioncontrol apparatus according to claim 2, wherein said switching means hasa slider which is slidable along the outer surface of said tube and acontrol button which causes said slider to slide in response to a manualoperation.
 7. A suction control apparatus provided on an control part ofan endoscope having a suction port at the distal end of an insert partthereof, comprising:a flexible tube communicating at the distal endthereof with said suction port and communicably connected at theproximal end thereof to a suction means; a cut made in the intermediateportion of said tube so as to extend obliquely from the proximal endside toward the distal end side of said tube; and switching means forcontacting said tube at said cut for switching over the following twostates from one to the other, that is, a stand-by state wherein saidtube is diametrically pressed at said cut from the side of said tube anda suction state wherein said tube is restored to its free state, therebyenabling suction to take place from the distal end side to the proximalend side of said tube.
 8. A suction control apparatus according to claim7, said tube having an outer surface and an inner surface, wherein aflap is formed at the distal end side of said cut, said flap having atip, whereby the outer surface of said tip is disposed at said innersurface of the proximal end side of said cut when said cut is closed. 9.A suction control apparatus provided on an control part of an endoscopehaving a suction port at the distal end of an insert part thereof,comprising:a flexible tube communicating at the distal end thereof withsaid suction port and communicably connected at the proximal end thereofto a suction means; a cut made in the intermediate portion of said tubeso as to extend obliquely from the proximal end side toward the distalend side of said tube; and switching means for contacting said tube atsaid cut for switching over the following two states from one to theother, that is, a stand-by state wherein said tube is diametricallypresses at said cut from the side of said tube where said cut isprovided so as to close the cut area which leads to the distal end ofsaid tube and a suction state wherein said tube is restored to its freestate, thereby enabling suction to take place from the distal end sideto the proximal end side of said tube.
 10. A suction control apparatusaccording to claim 9, wherein said tube is made of elastomer.
 11. Asuction control apparatus according to claim 9, wherein said cut is atan angle of from 15 to 60 degrees to the axis of said tube.
 12. Asuction control apparatus according to claim 11, wherein said cut is atan angle of 30 degrees to the axis of said tube.
 13. A suction controlapparatus according to claim 9, wherein said switching means has apressing plate which is slidable in the diametrical direction of saidtube so that said pressing plate can press said tube from the sidethereof where said cut is provided and thereby close said tube, and acontrol button which causes said pressing plate to slide in response toa manual operation.
 14. A suction control apparatus provided on acontrol part of an endoscope having a suction port at the distal end ofan insert part thereof, comprising:a flexible tube communicating at thedistal end thereof with said suction port and communicably connected atthe proximal end thereof to a suction means; a cut made in theintermediate portion of said tube so as to extend obliquely from theproximal end side toward the distal end side of said tube; and switchingmeans for switching over the following two states from one to the other,that is, a stand-by state wherein said tube is bent diametricallypressed at said cut from the side of said tube where said cut isprovided so as to close the cut area which leads to the distal end ofsaid tube and a suction state wherein said tube is restored to its freestate, thereby enabling suction to take place from the distal end sideto the proximal end side of said tube, wherein said switching means hasa pressing plate which is slidable in the diametrical direction of saidtube so that said pressing plate can press said tube from the sidethereof where said cut is provided and thereby close said tube, and acontrol button which causes said pressing plate to slide in response toa manual operation.
 15. A suction control apparatus according to claim14, wherein said pressing plate is provided with a bore for receivingsaid tube.
 16. A suction control apparatus according to claim 15,wherein one side of said bore is open so that said tube can be insertedinto and removed from said bore through the open portion.
 17. A suctioncontrol apparatus provided on an control part of an endoscope having asuction port at the distal end of an insert part thereof, comprising:aflexible tube communicating at the distal end thereof with said suctionport and communicably connected at the proximal end thereof to a suctionmeans; a cut made in the intermediate portion of said tube so as toextend obliquely from the proximal end side toward the distal end sideof said tube; and switching means for switching over the following twostates from one to the other, that is, a state wherein said tube is bentwith said cut facing outward and a state wherein said tube isstraightened at and near said cut, wherein said switching means includesa slider which is slidable along the outer surface of said tube and acontrol button which causes said slides to slide in response to manualoperation; whereby, when said tube is bent, said cut is opened andambient air is sucked into said tube through said cut, whereas, whensaid tube is straightened, said cut is closed and suction is performedthrough said suction port.
 18. A suction control apparatus according toclaim 17, wherein said slider has an annular configuration.
 19. Asuction control apparatus according to claim 17, wherein said slider hasa C-shaped cross-sectional configuration so that said tube can beattached to and removed from said slider through the opening in theC-shaped configuration.